1. Field of the Invention
This invention relates generally to the weighing of individual loads during continuous movement thereof, and more particularly to a weight measurement system for obtaining accurate weight data with respect to continuously moving products or the like suspended from a processing conveyor.
In the processing of products such as poultry, especially when performed on a large scale, it is becoming more essential from an economy and marketing standpoint that accurate weight measurements be obtained with respect to such products during continuous movement suspended from a processing conveyor. The weight measurements are utilized, for example, to sort or classify the products in connection with packaging, labeling and/or sale to consumers. The need for accuracy in weight measurement is apparent since the weight sorting operation is based on limited deviation of product weight from either center weight values within different weight ranges, or deviation from different weight limits. Accurate weight measurements are also essential where plural product weight totals are required.
2. Description of Related Art
The use of electronic load cells of the strain gauge type has come into wide use for product weighing purposes in the poultry processing art, aforementioned. The need for correcting such measurements through a data processing system because of various error producing factors, is well recognized as exemplified by the disclosures in U.S. Pat. Nos. 4,525,794 and 4,691,290 to Scheffer, et al, and Griffin, respectively. The use of electronic load cells and data processing systems in connection with poultry weight sorting operations is disclosed for example in U.S. Pat. Nos. 4,413,739 and 4,483,047 to Kohashi and Linville, Jr., respectively. The use of a plurality of load cells to provide a totalized target weight, on the other hand, is disclosed for example in U.S. Pat. Nos. 4,372,099, 4,388,975, 4,566,070 and 4,550,792 to Linville, Hirano, Tanaka and Mosher, et al, respectively.
One particular source of error in weight measurement arises because of load vibration on the load cell during the weighing operation, as recognized and dealt with in U.S. Pat. Nos. 4,347,903, 4,553,619 and 4,660,160 to Yano, et al, Fujinaga and Tajimia et al, respectively. According to the Tajimia patent, weight measurement display is limited to a correct measurement through time-controlled sampling and difference comparison in the data processing system. According to the Yano, et al and Fujinaga patents, a continuous analog output of the load cell is digitized, sampled and averaged in order to obtain correct weight measurement readout from the data processor.
Despite the recognized need for accuracy in weighing continuously moving objects such as poultry products suspended from a processing conveyor, and the availability of prior art data processing systems with error correcting capabilities, as aforementioned, the weight accuracy problem still persists. In the poultry processing art, such problem involves a host of variable and unpredictable error producing conditions including irregular load movement, equipment vibration, impacting debris and liquid particles, etc. Further, changing environmental conditions in any single processing plant and/or different conditions in different processing plants often renders the aforementioned prior art error correcting systems unfeasible from the standpoint of consistency, economy or installational adaptability.
It is therefore an important object of the present invention to provide a weight measurement system for moving conveyor suspended loads such as poultry products that is readily adaptable to different installational conditions in producing a high degree of consistent accuracy for the weight measurements obtained despite the presence of variable error-producing factors.